Device and method for positioning an electrode in tissue

ABSTRACT

A device for positioning an electrode in tissue includes: a lead body having a distal portion; an electrode array coupled to the lead distal portion; an anchoring element having an anchor tip and being operable in a first configuration in which the anchor tip is retracted within the lead and in a second configuration in which the anchor tip is extended outside the lead and configured to fixate within the tissue; and a displacement mechanism that is actuated to bias the electrode array or the anchoring element toward the tissue. A method for positioning an electrode in tissue includes: navigating, to the tissue, a lead with an electrode array, an anchoring element with a distal anchor tip, and a displacement mechanism; biasing the electrode array and anchoring element towards the tissue with the displacement mechanism; and deploying the anchoring element, and verifying fixation of the anchor tip within the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos.61/387,185 filed 28 Sep. 2010 (entitled “Rhythm Support Device 2”),61/412,992 filed 12 Nov. 2010 (entitled “Pacing Device”), 61/420,060filed 6 Dec. 2010 (entitled “Pacing Device”), 61/427,306 filed 27 Dec.2010 (entitled “Rhythm Support Device 5”), 61/445,992 filed 23 Feb. 2011(entitled “Pacing Device”), and 61/501,450 filed 27 Jun. 2011 (entitled“Pacing Device”). Each of these six provisional applications isincorporated in its entirety by this reference.

GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under contract TW008781awarded by the National Institutes of Health. The Government has certainrights in this invention.

TECHNICAL FIELD

This invention relates generally to the electrode stimulation devicefield, and more specifically to a new and useful system and method forpositioning an electrode in tissue in the electrode stimulation devicefield.

BACKGROUND

Bradycardia (reduced heart rate) is a common condition affectingmillions of patients annually. Although many such patients requireimplantation of permanent pacemaker devices to help regulate heart rate,other patients experience bradycardia with reversible causes that do notrequire permanent pacemaker implantation and may instead receivetemporary bradycardia support, such as over a period of less than oneweek. One common treatment for temporary bradycardia support involves asystem including transvenous electrode pacing leads that are inserteddirectly into the right ventricle of the heart to stimulate and regulatecardiac function. However, the conventional versions of these systemshave several drawbacks.

Thus, there is a need in the electrode stimulation device field tocreate a new and useful device and method for positioning an electrodein tissue in the electrode stimulation device field. This inventionprovides a new and useful device and method for positioning an electrodein tissue.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 and 2 are overall and detail views, respectively, of the systemof a preferred embodiment;

FIGS. 3A-3H are detailed views of variations of the lead body of thesystem of a preferred embodiment;

FIGS. 4-7 are variations of an atraumatic tip of the lead body of thesystem of a preferred embodiment;

FIGS. 8 and 9A-9D are an exploded view and longitudinal cross-sectionalviews of operation, respectively, of the handle in the system of apreferred embodiment;

FIGS. 10-13 are variations of the handle in the system of a preferredembodiment;

FIGS. 14A-14D are schematics of a process for assembling the electrodearray in the system of a preferred embodiment;

FIG. 15 is a schematic of a variation of the electrode array;

FIGS. 16A and 16B are schematics of the anchoring elements in the firstand second configurations, respectively, in the system of a preferredembodiment;

FIGS. 17-20 are variations of the anchoring elements in the system of apreferred embodiment;

FIGS. 21-24 are variations of verifying anchoring element fixation andelectrode array position in the system of a preferred embodiment;

FIGS. 25A and 25B are schematics of variations of the displacementmechanism arrangement in the system of a preferred embodiment;

FIGS. 26 and 27 are preferred and alternative variations of assemblingthe displacement mechanism;

FIGS. 28A and 28B are schematics of an example of the system of apreferred embodiment; and

FIGS. 29A-29F are schematics of the method of positioning an electrodein tissue of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of preferred embodiments of the invention isnot intended to limit the invention to these preferred embodiments, butrather to enable any person skilled in the art to make and use thisinvention.

1. Device for Positioning an Electrode in Tissue

As shown in FIG. 1, the device 100 of a preferred embodiment forpositioning an electrode in tissue includes: an elongate lead body 110having a distal portion 112; an electrode array 150 coupled to thedistal portion of the elongate lead body; an anchoring element 160disposed within the elongate lead body and having a distal anchor tip162, in which the anchoring element 160 is selectively operable in afirst configuration 164 in which the anchor tip is substantiallyretracted within the elongate lead body and in a second configuration166 in which the anchor tip is at least partially extended outside theelongate lead body and configured to fixate within the tissue 102; and adisplacement mechanism 170, coupled to the distal portion 112 of theelongate lead body 110, that is selectively expandable to bias theelectrode array 150 and/or the anchoring element 160 toward the tissue102. The device 100 may further include an actuator 140 disposed withinthe lead body 110 and abuttingly engaged with or otherwise coupled tothe anchoring element 160 to actuate the anchoring element 160 betweenthe first and second configurations. The device 100 may further includea handle 190 that is coupled to the elongate body and includes a slidecoupled to the actuator with first and second slide positionscorresponding to the first and second configurations of the anchoringelement, respectively.

The device is preferably used to securely place a pacing electrode leadin cardiac tissue, such as for temporary bradycardia support. The deviceenables reliable implantation and maintenance of the position of theelectrode lead. In particular, as shown in FIG. 2, the elongate body ispreferably navigable through the cardiovascular system (e.g. veins,arteries) into the right ventricle of the heart, such that when thedisplacement mechanism 170 is expanded, the electrode array 150 and/orone or more anchoring elements 160 are biased towards theintraventricular septum. The anchoring elements 160 are configured tofixate within tissue to secure the electrode array in contact with theintraventricular septum (tissue 102), which the electrode array maystimulate to help regulate heart rate. However, the device mayalternatively be used to secure any suitable electrode array in anysuitable tissue. For instance, in one variation (e.g. includes theelectrode array, anchoring elements and a mode of delivery such as acatheter, without including a displacement mechanism), the device may beused in applications such as laparoscopic surgery, general surgery,spinal surgery, and/or other procedures for any suitable tissue.

1.1 Lead Body

The elongate lead body 110 of the device functions to contain anddeliver the electrode array 150, anchoring element 160, and displacementmechanism 170 to target tissue within the body. The elongate lead bodyis preferably a steerable lead or other elongate body, such as acatheter with a stylet, preformed curve, or other internal steeringsystem. Such steering systems are known by one ordinarily skilled in theart, although the elongate body or lead may include any suitablesteering system for navigating in the cardiovascular system or otherportion of the body. The lead is preferably approximately cylindrical,but may alternatively be substantially flat or planar, or have anysuitable cross-section. The lead is preferably flexible and made of abiocompatible material such as polyurethane or polyimide, although atleast some portions may be rigid.

As shown in FIG. 3, the lead preferably includes a plurality of lumensthat carry control elements (e.g. steering elements, electricalconductors 116 coupled to the electrode array 150, anchoring elements160, actuator 140 coupled to the anchoring elements, and/or fluidchannel coupled to the displacement mechanism 170). At least some ofthese lumens may contain internal tubing within which a control elementis telescopically disposed. The lumens may be arranged in groups such asa first group including at least one lumen 132 for the actuator 140 andanchoring element 160, a second group including at least one lumen 134for the conductors 116 (potentially including a ground wire 118), and athird group including at least one lumen 136 for the fluid or otheractuator for the displacement mechanism. One or more of the lumensand/or internal tubing may be shaped with keys or other features toprevent rotation of control elements within the lead. For instance, asshown in FIG. 3C, the lumen 132 for the anchoring elements 160 may havean approximately rectangular cross-section to constrain alignment of theanchoring elements in a particular direction.

The first group of lumens passing along the lead preferably includes alumen 132 for the actuator 140. The actuator 140 is preferablylongitudinally translatable within the elongate body and abuttinglyengaged with the anchoring element 160 to actuate the anchoring elementbetween the first and second configurations. The actuator is preferablyflexible, to help keep the overall lead body 110 flexible, such as fornavigation through tissue and reduced tissue damage. In one variation,as shown in FIG. 3E, the actuator 140 includes at least a flexibleportion that includes a helical cut or groove path 142 passinglongitudinally along and circumferentially around the actuator. Forinstance, the actuator may include a wire portion disposed within orotherwise coupled to a tube portion having a helical cut 142. However,the actuator may have a series of circumferential rings, include pleatsor zig-zag cuts, or any suitable cuts and/or other features tocontribute to flexibility of the actuator. In another variation, theactuator is additionally and/or alternatively made of mesh or flexiblematerial.

The first group of lumens preferably further includes a lumen 132 forthe anchoring elements 160 extending from, and approximately concentricwith, the lumen 132 for the actuator 140. Between the lumens for theanchoring elements and actuator, the lead preferably further includes asleeve 144 that functions to decouple the anchoring elements fromrotation of the actuator and/or lead. In a preferred variation, as shownin FIG. 3A, the sleeve is fixed to the anchoring elements 160 and notfixed to the actuator 140, such that the actuator 140 is free to rotateindependently from the anchoring elements within the sleeve 144 and theactuator 140 is free to translate to abuttingly engage the anchoringelements 160. For instance, an abutting cylinder 146 coupled to thedistal end of the actuator 140 is preferably configured to push and/orpull the anchoring elements 160 within the lead body 110. Alternatively,the actuator 140 may be fastened to the sleeve and the anchoring elementmay be not fastened to the sleeve. In further alternative variations,both the actuator and the anchoring elements may be fastened (FIG. 3D)or unfastened to the sleeve 144, or coupled to the sleeve in anysuitable manner. In another alternative variation, the actuator 140 maybe coupled directly to the anchoring elements 160 (e.g. crimping,welding) or be integrally formed from the same piece as the anchoringelements. The actuator 140 and/or anchoring element 160 may be fastenedto the sleeve by a snap lock such as a ball joint, crimping, fastenersor adhesive.

The second group of lumens preferably includes one or more lumens 134for the conductors 116 that carry a current and/or a ground lead 118.The conductors are preferably wires made of an electrically conductivematerial, but may be tubing or another elongate shape. As shown in FIG.1, the proximal ends of the conductors are preferably coupled togenerator electrodes 199 and a power source P that are external to thepatient, and the distal end of the conductors are preferably coupled tothe electrode array 150. In one variation, the device may include onecurrent-carrying conductive lead per electrode in the electrode arraysuch that each electrode can be individually controlled. In a secondvariation, at least a portion of the current-carrying conductors may becoupled to multiple electrodes. In a third variation, at least a portionof the current-carrying conductors may be coupled directly to anelectrode, which is in turn coupled to one or more additional electrodessuch that at least a portion of the current-carrying conductors isindirectly coupled to one or more electrodes. However, the device mayinclude any suitable ratio of conductors to electrodes in the electrodearray, and in any suitable arrangement.

The third group of lumens passing along the lead preferably includes oneor more lumens 136 for an actuator of the displacement mechanism 170. Ina preferred variation, the third group of lumens includes a lumen orchannel that carries a fluid (preferably air) that may be used to expandthe displacement mechanism. In this variation, as shown in FIG. 1, theproximal end of the fluid-carrying lumen may be coupled to a syringe orother pump 197 that displaces fluid through the fluid-carrying lumen136, and the distal end of the fluid-carrying lumen may be coupled tothe displacement mechanism 170. In other variations, the third group oflumens may carry wires, rods, springs or any suitable actuator for theparticular kind of displacement mechanism in the device.

In a preferred embodiment, as shown in FIGS. 3B-3C, the first group oflumens (including a lumen for housing the actuator 140 and anchoringelements 160) is a central lumen 132 passing approximately axially alongthe lead body 110, and the second and third groups of lumens (housingthe conductors and displacement mechanism actuator) are peripherallumens 134 and 136 that are circumferentially distributed around thecentral lumen 132. Alternatively, as shown in FIG. 3F the lumen 132 forhousing the actuator and anchoring elements may be off-center, and thesecond and/or third groups of lumens 134 and 136 may be arranged inother off-center lumens. However, any of the groups may be distributed,combined or otherwise arranged in any suitable manner.

As shown in FIG. 1, the lead preferably further includes a distalportion 112 to which the electrode array 150, one or more anchoringelements 160, and one or more displacement mechanisms are coupled. Asshown in FIG. 3G, the distal portion defines one or more apertures 133through which the anchoring elements 160 deploy, preferably defining oneaperture 133 per anchoring element but alternatively the ratio ofapertures 133 to anchoring elements may be less than or greater than1:1. Similarly, the distal portion 112 preferably defines one or moreapertures 135 through which the conductors 116 extend to couple to theelectrode array, with one aperture 135 per conductive lead, or with theratio of apertures to conductors less than or greater than 1:1.Alternatively, the distal portions of the conductors may remain withinthe elongate lead body 110, and the electrode array 150 or otherinterconnects may extend through the apertures 135 into the elongatelead body to couple to the conductors. Similarly, the distal portion 112preferably defines at least one aperture 137 through which air oranother fluid actuates the displacement mechanism. As shown in FIG. 3H,the distal portion 112 or other portions of the lead may also includecontrast markers 124 made of a material that is visible underfluoroscopy, such as to aid visual confirmation of device position orplacement.

The distal portion 112 of the lead preferably further includes anatraumatic tip 114, which functions to reduce or eliminate thelikelihood of perforation or other damage to the tissue as the lead isnavigated through tissue. The atraumatic tip 114 absorbs at leastsubstantially frontal forces (longitudinal force in a proximaldirection), and more preferably forces in additional directions. Theatraumatic tip 114 may include softer, impact-absorbing material such aselastomer with a relatively low durometer, and/or may include geometryto help absorb forces. In a preferred embodiment, as shown in FIGS. 4Aand 4B, the atraumatic tip 114 includes a hollow tubular structure. Thehollow tubular structure is preferably somewhat narrow and elongate in afree uncompressed mode (FIG. 4A) relative to when in a compressed mode(FIG. 4B) such as when the atraumatic tip 114 encounters the rightventricle or other tissue). When the atraumatic tip is compressed, thehollow tubular structure preferably flares radially and increasessurface are potentially in contact the tissue, thereby reducing risk ofperformation. The atraumatic tip 114 may additionally and/oralternatively include one or more features of several variations. In afirst class of variations, the atraumatic tip 114 includes otherversions of an expandable tip, such as an expandable cap (“mushroom”shape) as shown in FIGS. 5A and 5B, expandable “umbrella” tines as shownin FIG. 5C, “peeling” tines as shown in FIGS. 6A and 6B or a distalballoon as shown in FIG. 7C. In a second class of variations, theatraumatic tip deforms in a curled manner upon experiencing frontalforces. In one example, as shown in FIG. 7A, the atraumatic tip mayinclude a flexible tip that curls when experiencing frontal forces, andmay further include an internal stylet that helps direct the curling ofthe flexible tip as the tip absorbs force. In another example, as shownin FIG. 7B, the atraumatic tip may includes notches that bias the tip tocurl in a particular direction to absorb force. In a third class ofvariations, as shown in FIG. 7D, the atraumatic tip may include a soft,compressible material and/or have a rounded (e.g. hemispherical) orsmooth shape.

The device preferably further includes a handle 190 coupled to the leadbody 110. As shown in FIG. 1, the handle is preferably coupled in-lineto the lead body such that rotation of the handle corresponds torotation of the lead body, although the handle may alternatively becoupled to the lead body 110 in any suitable manner. The handle 190 ispreferably a tubular housing that contains the actuator, the conductors,and/or actuator for the displacement mechanism 170. As shown in FIGS.8-9, the overall shape of the handle is preferably cylindrical (e.g.somewhat pen-shaped), with a tapered distal end from which the elongatelead body extends, but alternatively may be a bar-shaped handle, across-shape, somewhat planar, or have any suitable cross-section oroverall shape. The handle 190 includes a slide 194 coupled to theactuator 140 with first and second slide positions corresponding to thefirst and second configurations of the anchoring element, respectively.As shown in FIG. 9A, the handle 190 further includes a trigger release195 that selectively engages the slide 194, such that when the triggerrelease is engaged with the slide, the slide is constrained in the firstslide position, thereby keeping the anchoring element in the secondconfiguration. In a preferred embodiment, the slide 194 is biased (suchas spring-loaded with spring 193) towards the second slide position,such that when the trigger release is disengaged from the slide (FIG.9B), the slide is loaded to forcefully travel from the first slideposition to the second slide position (FIG. 9C), thereby deploying theanchoring element from the lead body. Alternatively, when the triggerrelease is disengaged from the slide, the slide may be freely movable bythe user between the first and second slide positions. The triggerrelease 195 is preferably a button that provides a first stop to preventslide movement from the first slide position to the second position(FIG. 9A) and a second stop to prevent slide movement further distalthan the second position (i.e. restrain the slide in the second positionas in FIG. 9D). The handle 190 preferably further includes a reloadswitch 196 that retracts the slide from the second slide position to thefirst slide position, thereby retracting the anchoring elements into thelead body (FIG. 9D).

In an alternative embodiment, as shown in FIGS. 10A-10E, the handle maybe a cross-shaped handle 190′ in which the reload switch 196 isdecoupled from the slide 194 such that when the trigger release 195 isdisengaged from the slide 194 (FIG. 10B), the slide is loaded (e.g.,with spring 193) to travel from the first slide position to the secondslide position (FIG. 10C), without effecting corresponding movement ofthe reload switch 196. Similar to the preferred embodiment of thehandle, the reload switch 196 retracts the slide from the second slideposition to the first slide position, thereby retracting the anchoringelements into the lead body (FIG. 10D) and enabling the trigger release195 to reengage with the slide for a repeated deployment of theanchoring elements (FIG. 10E). By default, the reload switch is in the“ready to reload” position shown in FIGS. 10B and 10C.

The handle 190 may further include a septum 198 that reduces likelihoodof blood and other fluids from entering the lead body 110 (e.g. throughapertures of the anchoring elements 160) when the lead body is placedwithin the body. The septum 198 prevents a pressure gradient betweeninside the lead body 110 and outside environment (e.g. right ventricle),such that fluids do not travel into the lead. As shown in FIG. 11, in apreferred embodiment, the septum 198 is coupled to the tapered distalend of the handle and includes a thin membrane that the slide oractuator (e.g. wire portion of the actuator) can penetrate and travelthrough with little friction during anchoring element deployment andretraction. Alternatively, the septum 198 may be coupled to the insideof the lead at any location along the lead. The septum is preferablymade of an elastomeric material. However, the septum may alternativelyinclude any suitable structure and/or material that prevents a pressuredifference between the inside and outside of the lead, therebypreventing fluid migration through the lumens of the lead.

In some embodiments, the handle 190 is detachable from the lead. Forinstance, the handle may be detached after the anchoring elements aredeployed and the electrode array 150 is fixated in the desired position.After the electrical lead has served its purpose and the anchoringelements are ready to be retracted from the tissue, the handle may bereattached to the lead. In these embodiments, the handle 190 may be areusable tool that is sterilized and reused with multiple implantablelead devices (which may be disposable devices), although both the handleand lead may be disposable. In these embodiments, as shown in FIGS. 12Aand 12B, the handle 190 may include a compartment accessible by a hingedcover and enables access to decouple particular mechanisms. In a firstvariation, as shown in FIG. 12C, the actuator 140 is decoupleable fromthe slide, thereby decoupling the lead 110 from the handle. In a secondvariation, the actuator 140 is decoupleable from the sleeve 144 and/oranchoring element 160, such that the handle and actuator may be pulledin a proximal direction away from the lead to decouple from the lead 110as shown in FIG. 12D, thereby decoupling the lead from the handle.However, the handle may be detachable from the lead in any suitablemanner.

As shown in FIG. 1, generator electrodes and the fluid pump (e.g.syringe), coupled to the conductors and displacement mechanism actuator,respectively, are preferably located proximal to and aligned with thehandle 190. However, as shown in FIG. 13A, in an alternative embodimentthe generator electrodes, fluid pump 197 for the displacement mechanism,and/or fluid pump 197′ for contrast fluid are coupled to the lead body110 near the handle 190, such as at a junction with a Y-connector orother suitable connector. As shown in FIG. 13B, the generator electrodes199 and/or fluid pumps 197 and 197′ may be decoupled from the handle190. For instance, the proximal end of the handle 190 may include portsthat receive generator electrode plugs and fluid supply (e.g. luer lockcoupling) for the displacement mechanism 170.

1.2 Electrode Array

The electrode array 150 functions to provide a stimulation current totarget tissue. As shown in FIG. 14, the electrode array preferablyincludes one or more stimulation electrodes arranged on the distalportion 112 of the lead body 110. In particular, the electrodes may bepacing electrodes for temporary support of bradycardia, but mayadditionally and/or alternatively be any suitable kind of electrodes. Ina preferred embodiment, the electrodes are ring or bands arrangedserially along the length of the lead body 110, but may additionallyand/or alternatively include any suitable electrodes of other shapes(e.g planar, circular, elliptical) arranged in any suitable manner. Forinstance, as shown in FIG. 15, the electrode array 150 may include anelectrode on the distal tip of the lead. In one preferred embodiment,the electrode array 150 includes two ring electrodes 152 arranged on thedistal portion 112 of the lead body 110.

During manufacture and assembly of the device, the electrodes are placedin electrical contact with the conductors 116 that carry current alongthe lead body. As shown in FIG. 14A, the conductors are preferablypassed along respective lumens within the lead body and extended outsidethe lead body through respective apertures. The extended ends of theconductors are wrapped circumferentially around the lead body, and thering electrodes are slipped over the lead body 110 and over the wrappedconductors (FIG. 14B). The electrodes may be secured over the wrappedconductors with epoxy or crimping, and then swaged or otherwise modifieduntil the outer diameter of the ring electrodes is substantially equalto the diameter of the lead body, such that the electrodes lie flushwith the lead body. However, the electrode array and the lead may bemanufactured and assembled in any suitable method.

1.3 Anchoring Element

The anchoring elements 160 of the device function to fixate with tissue,thereby securing the electrode array 150 adjacent to target tissue. Thedevice may include one or multiple anchoring elements, each with ananchoring element body and an anchor tip 162. As shown in FIG. 16, theanchoring elements 160 selectively operate between a first and secondconfiguration, where the anchoring elements are preferably operated inthe first configuration 164 while the lead is navigated in tissue to thetarget tissue, and in the second configuration 166 when the lead isadjacent to the target tissue, although the anchoring elements may beoperated in any suitable manner. In one embodiment, the first and secondconfigurations are “deployed” and “retracted” modes, respectively, ofthe anchoring elements. In the first configuration 164 the anchoringelement is positioned at a first anchoring element position within thelead body 110, and the anchor tip 162 is substantially retracted withinthe lead body (FIG. 16A). In the second configuration 166, the anchoringelement is positioned at a second anchoring element position within thelead body 110 and the anchor tip 162 is at least partially extendedoutside the lead body and configured to fixate within tissue (FIG. 16B).The second anchoring element position is preferably distal to the firstanchoring element position, such that transition from the firstconfiguration to the second configuration corresponds to a distalmovement of the anchoring element (and the actuator 140, which ispreferably coupled to the anchoring elements 160). However, in othervariations the transition from the first configuration to the secondconfiguration may correspond to any other suitable kinds of movement(e.g. proximal, rotational) movement of the anchoring element.

The device preferably includes a plurality of anchoring elements 160,although in some embodiments the device may includes only one anchoringelement. In a first variation, the anchoring elements are longitudinallyaligned such that the anchor tips deploy in approximately the samedirection (FIG. 16). In a second variation, the anchoring elements arelaterally aligned and circumferentially distributed around the lead body110 (FIG. 17A). In a third variation, the anchoring elements aredistributed both longitudinally along and circumferentially around thelead body 110, such as in a staggered arrangement (FIG. 17B) or spiralarrangement (FIG. 17C). Furthermore, as shown in FIGS. 18 and 19, theplurality of anchoring elements 160 may be located along the lead body110 between electrodes, alternating with electrodes, and/or proximal anddistal to electrodes (with electrodes between the anchoring elements).In a specific preferred embodiment, the device includes two anchoringelements longitudinally aligned with one another and located on thedistal portion 112 of the lead body between the two ring electrodes. Atleast a portion of the anchoring elements may additionally and/oralternatively be coupled to a surface (e.g. outer or underside) of thedisplacement mechanism 170 (FIG. 18E), or on the distal tip of the leadbody. However, the device may include any suitable number of anchoringelements on any suitable portion of the lead body and/or displacementmechanism or other portion of the device, which may depend on theapplication of the device.

In an alternative embodiment, one or more anchoring elements 160 mayadditionally and/or alternatively function as an electrode to replace orsupplement the functionality of the electrode array 150. For example, ananchoring element may include an electrically conductive alloy or othermaterial such as tantalum, where the anchoring element is wholly madeof, embedded with, or coated with the electrically conductive material.This alternative embodiment of the device may include various relativepositions of anchoring elements, electrodes, and the displacementmechanism. For example, as shown in FIG. 19A, the lead body 110 mayinclude anchoring elements 160 (functioning as electrodes) proximaland/or distal to the displacement mechanism 170, without additional,separate electrodes. As shown in FIGS. 19B and 19C, the lead body 110may include both an anchoring element functioning as an electrode, aseparate ring electrode, and/or an anchoring element on the distal tipof the lead body.

The anchor tip 162 of an anchoring element is preferably uncurled in thefirst configuration, located within a lumen of the lead body 110. Asshown in FIG. 20A, the anchor tip 162 preferably has a biased cut 168forming a sharpened point, with the bias cut angled such that when theanchor tip is retracted within the lead body 110, the cut issubstantially parallel to the wall of the lumen and may smoothly slidealong the wall to reduce the friction between the anchor tip and thewall of the surrounding lumen and reduce force requirements fordeployment. However, the bias cut may be angled at any suitable angle.In one embodiment, when transitioning to the second configuration, theanchor tip 162 preferably curls upon itself in at least a partial loop(e.g. partially circular loop such as “U”-shaped or “J”-shaped, orpartial loop of other shapes such as triangle or square), such thatafter the sharpened point pierces the tissue, further deployment of theanchoring element results in the anchor tip burrowing and fixating in acurled manner. The curled shape or state helps reduce shifting ordislodgement of the anchor tip in that it is resistant to forces in manydirections. As shown in FIG. 20B, in the second configuration the anchortip 162 is preferably curled in a circular loop having uniform radius ofcurvature, although as shown in FIG. 20C, alternatively the radius ofcurvature may vary (e.g. spiral inwards). The anchor tip 162 may curl orbend in such a manner as to cross or overlap with itself. The anchor tip162 may also bend in such a manner as to trace a path that returnstoward the lead body, such as to contact the external portion of thelead body and/or re-enter the lead body. Retraction of the anchoringelement after deployment withdraws the curled anchor tip in a reversedirection in the path that it burrowed during deployment and restoresthe anchor tip in a straightened shape within the lead body. In apreferred embodiment, uncurled refers to the relative configuration ofthe anchor tip 162 when substantially retracted within the elongatebody. Curled refers to the relative configuration of the anchor tip 162when at least partially extended outside the elongate body. The shape ofthe anchor tip 162 in the first and second configurations may be of oneor more of several variations, although it may be any suitable shape. Inalternative variations, as shown in FIG. 20D, the anchor tip mayadditionally and/or alternatively include hooks, barbs (e.g. acutebends) or other fixation features in any suitable shape. Furthermore,the anchor tip 162 may include bioresorbable material such that after acertain amount of time, the anchor tip dissolves and is absorbed intothe body, and/or may include material that promotes or prevents tissueadhesion. The anchoring elements 160 are preferably made of nitinol wireor other biocompatible shape memory alloy, but may alternatively beformed wire and/or coated with any suitable biocompatible material. Inan alternative variation, the anchoring elements may be of variablestiffness along the length, such as by allowing gel infusion intoselected portions of the anchoring element or conducting an electricalsignal to electrically-sensitive material to vary rigidity.

The anchoring elements 160 are preferably deployed and retracted, asdescribed above, by spring-loaded or manually controlled longitudinalmovement of the actuator within the lead body 110. However, in anothervariation, the anchor tips may be coupled to the displacement mechanism170, such that when the displacement mechanism expands, the anchor tipsare deployed and fixated within the tissue. In other variations, theanchoring elements may be actuated with any suitable mechanism, such ascords. Furthermore, the deployment and retraction of the anchoringelements may be triggered by a manual action specifically for theanchoring elements (e.g. button or slide on the handle 190) and/orautomatic means (e.g. triggered by expansion or unexpansion of thedisplacement mechanism or based on existence of electrical contactbetween the anchoring element and the electrode array).

The device preferably further includes one or more mechanisms forverifying anchoring element deployment and fixation in tissue, which mayadditionally and/or alternatively be modified for verifying anchoringelement retraction and removal from tissue (such as before removal ofthe lead from the patient). Furthermore, the anchor deploymentverification mechanism may further function to verify the position ofthe electrode array 150 relative to tissue. As shown in FIG. 21, in onevariation, the anchor deployment verification mechanism includes a fluidinjection port in the lead body that enables release of fluoroscopiccontrast fluid under fluoroscopy. For example, the apertures from whichthe anchoring elements deploy may enable contrast fluid 122 to flow outof the lead. When the anchoring elements 160 are not fixated in tissue,the released contrast fluid will at least initially tend to diffuse inapproximately the same direction as the anchoring element deployment(FIG. 21A). When the anchoring elements 160 are fixated in tissue, thereleased contrast fluid flow will initially be blocked by the tissue andflow away from the tissue (FIG. 22B). Monitoring the flow of contrastfluid and/or using the contrast fluid to visualize the targetenvironment (e.g., right ventricle) under fluoroscopy aids visualconfirmation of anchor tip fixation in tissue 102. The contrast fluidinjection may be manually controlled such as with syringe 197′ and/orautomatically triggered by another action, such as deployment ofanchoring elements.

Another variation of the anchor deployment verification mechanismincludes an electrical feedback circuit including one or more of theanchoring elements and one or more electrodes in the electrode array150. As shown in FIG. 22A, when a deployed anchor tip is not properlyfixated in tissue, contact between the deployed anchor tip and a nearbyelectrode on the lead body triggers a switch on the electrical feedbackcircuit that is used to signal the error in anchor tip fixation. Asshown in FIG. 22B, when the deployed anchor tip is properly fixated intissue, the tissue prevents contact between the deployed anchor tip andthe electrode and leaves the switch open, which is used to signalcorrect anchor tip fixation. Implementation of this switch to anexternal electrical system is known and readily understood by oneordinarily skilled in the art.

As shown in FIG. 23, another variation of the anchor deploymentverification mechanism includes at least two sets of electrical padpairs on the lead body 110, including: a distal pad pair 128 d near andon the same side as the anchoring elements 160 and electrodes andconfigured to contact the tissue, and a proximal pad pair 128 p on anopposite side of the anchoring elements 160 and configured to face awayfrom the tissue. The electrical pad pairs provide outputs of Vd (voltageoutput across the distal pad pair) and Vp (voltage output across theproximal pad pair). When the anchor tips are not properly fixated andthe electrodes are not in contact with the tissue, Vd=Vp (approximately)because both electrical pad pairs are in contact with the sameenvironment (e.g. blood, but not in contact with tissue). When theanchor tips are properly fixated and the electrodes are in contact withthe tissue, Vd>Vp due to the impedance of the tissue in contact with thedistal pad pair. The ratio between Vd and Vp (or the absolute orrelative difference between Vd and Vp) can be displayed on a real-timegraph, or other display such as an LED display or LCD screen, to theuser operating the device in a patient, such that the change in theratio results in a change in the displayed signal and, when the signaldifference surpasses a particular threshold, the signal indicates tissuecontact with the distal electrical pad pair 128 d, anchor tips 162, andelectrode array 150.

Another variation of the anchor deployment verification mechanismincludes pressure sensors. In one version, as shown in FIG. 24, apressure sensor 126 is coupled to the lead body 110 and senses when thetissue is in contact when the lead body. In other versions, the pressuresensor may be coupled to the anchoring element, the electrode array 150,or any suitable portion of the device. Furthermore, although the anchordeployment verification mechanism is preferably one or more of thesevariations, the mechanism may additionally and/or alternatively be anysuitable mechanism.

1.4 Displacement Mechanism

The displacement mechanism 170 functions to bias the electrode array 150and/or anchoring elements, or other portion of the lead body, in aparticular direction, preferably toward the tissue. As shown in FIGS.21-24, the displacement mechanism is preferably coupled at leastpartially circumferentially around the distal portion of the lead body110, and more preferably on at least a side of the lead body oppositethe electrode array and/or anchoring elements. The displacementmechanism may additionally and/or alternatively be coupled to the leadbody on the same side as the anchoring elements (e.g. the anchoringelements 160 may be coupled to the outer side of the displacementmechanism 170), or circumferentially offset from the anchoring elementsby approximately 90 degrees (FIG. 25A) or any other suitable angle. Thedisplacement mechanism 170 may be selectively unexpandable to reversethe bias of the electrode array 150 and/or anchoring elements 160, suchas after the deployment and fixation of the anchoring elements in thetissue. The device preferably includes one displacement mechanism 170,but may include multiple displacement mechanisms arranged on the leadbody in any suitable arrangement; for example, as shown in FIG. 25B, thedevice may include a proximal displacement mechanism 170 locatedproximal to the electrode array and anchoring elements, and a distaldisplacement mechanism 170′ located distal to the electrode array andanchoring elements.

The displacement mechanism 170 preferably includes a balloon 172 that isselectively inflatable through a fluid channel in the lead body 100. Theballoon is preferably made of an elastomeric material such as silicon orpolyurethane, but may alternatively be made of any suitable material. Asshown in FIG. 26, in a preferred embodiment the balloon may includecircumferential bands 174 that slip over the lead and are sealed tocouple the balloon to the lead. A preferred method of manufacture of thedisplacement mechanism includes cutting two partially circumferentialslits 178 along the length of a tube 176 (FIG. 26A), folding the centralportion between the slits inwards to form two circumferential bands 174at each end of the tube (FIG. 26B), sliding the distal portion of thelead body 110 into the circumferential band, and sealing the edges ofthe tube to the lead body (FIG. 26C). The lead body preferably includesan aperture 137, located underneath with a portion of the balloon, thatprovides air or other fluid to inflate the balloon 172 (FIG. 26D).Alternatively, the balloon may be constructed from sheets. At least twosheets 180 may be sealed together face-to-face around their periphery toform an inflatable volume that is coupled to the lead body 110 and hasan aperture aligned with an aperture in the lead body, such that air orother fluid in the fluid channel in the lead body passes through theapertures of the lead body and inflatable volume to expand theinflatable volume. In a first variation, as shown in FIG. 27A, theinflatable volume is made from rectangular sheets and bonded to atubular band that slips over and couples to the distal portion 112 ofthe lead body, and the tubular band 182 has an aperture that aligns withthe other apertures to enable expansion of the inflatable volume. In asecond variation, as shown in FIG. 27B, the inflatable volume is made ofsheets with one or more extensions 184 (e.g. “I”-shaped, “H-shaped”,“E”-shaped or “L”-shaped sheets) that are wrapped around the lead bodyto form the circumferential bands. In an alternative embodiment, theballoon is an approximately spherical or spheroidal volume, or anotherkind of inflatable volume that is coupled to the fluid channel of thelead body.

In alternative variations, the displacement mechanism 170 may be otherexpandable mechanisms, such as an expandable and retractable ring,scaffold, or coil. In some embodiments, the device may further include amechanism for verifying displacement mechanism expansion and/orretraction. For instance, the displacement mechanism may includecontrast markers to visually aid confirmation of displacement mechanismexpansion/retraction under fluoroscopy. In other variations, themechanism for verifying displacement mechanism expansion/retraction maybe similar to the anchor deployment verification mechanism.

Alternative embodiments of the device 100 may include any combination ofthe variations of the lead body, handle, electrode array, anchoringelement, displacement device, and other mechanisms described above, andmay include additional suitable variations of such mechanisms and othersuitable modifications.

2. Example of an Embodiment of the Device

In an example of an embodiment of the device, the device includes ahandle, an elongate tubular pellethane lead body distally coupled to thehandle and having a distal portion that defines a plurality ofapertures, including two conductive lead apertures, two anchoringelement apertures, and an air aperture. As shown in FIGS. 28A and 28B,coupled to the distal portion of the lead body are: two stimulatingelectrodes suitable for pacing cardiac rhythm, two nitinol anchoringelements with anchor tips that selectively deploy out of the lead bodythrough respective anchoring element apertures, and an inflatableballoon coupled to the lead body on a side opposite the anchoringelement apertures. The lead has an atraumatic tip including soft,compressible material. The two stimulating electrodes are platinum ringelectrodes located approximately 10 mm apart. The two anchoring elementapertures, which are approximately 1.5 mm long, are located between theelectrodes, with the proximal anchoring element aperture locatedapproximately 3.5 mm distal to the proximal electrode, and the distalanchoring element aperture located approximately 3.5 mm distal to theproximal anchoring element aperture. The inflatable balloon, which isapproximately 16.5 mm long and selectively inflatable to bias the distalportion of the lead body in a particular direction toward tissue, ismade from silicon tubing and includes two circumferential bands and acentral portion between the bands. The proximal circumferential band ofthe balloon is approximately 3.5 mm long and is located approximately1.25 mm proximal to the proximal electrode, and includes an aperturefluidically coupled to an air supply. The distal circumferential band ofthe balloon is approximately 3 mm long and located approximately 1.25 mmdistal to the distal electrode. Each anchoring element is made of 0.008in diameter nitinol wire and selectively operates in a retracted modeand in a deployed mode. The anchor tips of the anchoring elements arecoated with a radio-opaque material visualizable under fluoroscopy. Inthe retracted mode, each anchoring element is at a proximal position inthe lead body and the anchor tip is uncurled and sheathed within thelead body. In the deployed mode, each anchoring element is at a distalposition in the lead body and the anchor tip is in a curled loopconfigured to fixate within the tissue.

The lead body defines a plurality of lumens, including a lumen receivingan actuator (stainless steel push wire with an outside diameter of 0.018in and crimped to a stainless steel cylindrical tube with an outsidediameter of 0.025 in and inside diameter of 0.020″) that pushes theanchoring elements in a distal direction to deploy the anchor tips, atleast two lumens each for receiving a conductive lead that extendlaterally outside the lead body and couple to respective ringelectrodes, and a lumen for carrying fluid to inflate the balloon. Theactuator includes a sleeve or collar (stainless steel tube with anoutside diameter of 0.032 in and inside diameter of 0.029 in) that iscoupled to the anchoring elements, but decoupled from the actuator.Additional dimensions of the lead body are shown in FIGS. 28A and 28B.

The handle is pen-shaped and includes a trigger release button that iscoupled to a spring-loaded slide that, when released, transitions theanchoring elements from the retracted mode to the deployed mode. Whenthe trigger release is freed, the slide slides from a proximal slideposition to a distal slide position corresponding to the retracted modeand deployed modes, respectively, of the anchoring elements. Thespring-loaded slide enables the actuator to push the anchoring elementsfrom the proximal position to the distal position, thereby launching theanchor tips into the curled, deployed position. The handle furtherincludes a reload switch that retracts the slide from the second slideposition to the first slide position. The handle is distally removablycoupled to an air supply (syringe) that provides air for inflating theballoon, and further distally removably coupled to generator electrodesthat provide current to the electrodes.

3. Method for Positioning an Electrode in Tissue

As shown in FIGS. 29A-29F, the method 200 for positioning an electrodein tissue in a body includes: navigating, to a location adjacent to thetissue, an elongate lead body with an electrode array, at least oneanchoring element with a distal anchor tip, and a displacement mechanismS210, biasing the electrode array and/or at least one anchoring elementtowards the tissue with the displacement mechanism S220, deploying atleast one anchoring element S230 and allowing the anchor tip to fixatewithin the tissue S240. The method may further include verifyingposition of the electrode array relative to the tissue S250 andverifying fixation of the anchor tip within the tissue S260. In apreferred embodiment, the method 200 is used to provide temporary pacingguidance from pacing electrodes in support of bradycardia, although themethod may alternatively be used in any suitable electrode application.In an alternative embodiment, the method includes the step of biasingthe electrode array and/or at least one anchoring element towards thetissue by deploying at least one anchoring element.

Navigating the lead body to the tissue S210 is a step known to oneordinarily skilled in the art, and may include steps such asmanipulating a handle coupled to the lead, manipulating a stylet, andactivating steering wires. However, any suitable steps may be performed,depending on the exact design of the lead body (e.g. steerable lead,pre-formed curve, stylet) and/or applications of the lead in varyingembodiments. Navigation may utilize fluoroscope, ultrasound, or othervisual modalities. In the preferred embodiment, as shown in FIG. 29A,navigating the lead body includes navigating the lead body through bloodvessels towards the heart.

Biasing the electrode array and/or at least one anchoring elementtowards the tissue S220 functions to encourage direct contact betweenthe electrode array and/or anchoring elements and the tissue, whichimproves fixation of the anchoring element within the tissue. As shownin FIG. 29B, biasing the electrode array preferably includes expandingthe displacement mechanism S222. In a preferred variation, expanding thedisplacement mechanism includes inflating a balloon, such as with asyringe, pump, or manual actuation. The balloon may be on a side of thelead body opposing the anchoring elements such that the balloon pushesagainst a wall opposing the tissue (e.g. wall of the right ventricleopposing the interventricular septum) to displace the lead body (alongwith the electrode array and anchoring elements) towards the tissue. Inother words, expanding the displacement mechanism includes expanding thedisplacement mechanism substantially opposite the direction of anchoringelement deployment. In other alternative variations, biasing theelectrode array and/or at least one anchoring element towards the tissueincludes expanding a ring, scaffold, coil, or other suitable expandingmechanism in any suitable direction.

In some embodiments, as shown in FIG. 29C, biasing the electrode arrayand/or at least one anchoring element towards the tissue additionallyand/or alternatively includes biasing the tissue towards the lead bodyS224. For instance, biasing the tissue towards the lead body may includeapplying suction to pull the tissue towards the lead body (e.g. into theanchoring element apertures or other apertures), or providing pressureon the backside of the tissue (e.g. left ventricle side of theinterventricular septum).

As shown in FIG. 29D, deploying at least one anchoring element S230 andallowing the anchor tip to fixate within the tissue S240 function tosecure the electrode array in contact with the tissue. Deploying theanchoring element preferably includes freeing a trigger release, such asa button or slider, that releases a spring-loaded actuator to actuatethe anchoring elements from the first configuration to the secondconfiguration. However, the actuator may be actuated with a stylet,cords, or any suitable mechanism. Furthermore, in alternativevariations, deploying the anchoring element may include any suitableactuation step that transitions the anchoring element from the firstconfiguration to the second configuration. Allowing the anchor tip tofixate within the tissue preferably includes allowing the anchor tip tocurl into a loop within the tissue, or additionally and/or alternativelyincludes allowing the anchor tip to engage barbs, hooks, or otherfixation features within the tissue.

As shown in FIG. 29E, verifying position of the electrode array relativeto the tissue and verifying fixation of the anchor tip within the tissuefunction to confirm location of the electrode array (and potentiallyother portions of the lead body). These verifying steps may additionallyand/or alternatively function to confirm proper secure deployment of theanchoring elements within the tissue. In a first variation, verifyingsteps S250 and S260 include monitoring location of contrast markerscoupled to at least a portion of the lead body (lead, electrode array,anchoring elements or displacement mechanism) under fluoroscopy, such asmonitoring a display that provides visualization of the contrast markersunder fluoroscopy. In a second variation, as shown in FIGURE verifyingsteps S250 and S260 include releasing contrast fluid and monitoring forobstructed path of the contrast flow under fluoroscopy. In a thirdvariation, verifying steps S250 and S260 include receiving an electricalsignal that signifies when the anchoring element is in the secondconfiguration and fixated in the tissue. In a fourth variation,verifying steps S250 and S260 include measuring a first electricalmeasure (e.g. voltage, impedance) across a first set of contact pointsintended to be in contact with the tissue, measuring a second electricalmeasure across second contact points intended to not be in contact withthe tissue, and monitoring a comparison between the first and secondelectrical measures. However, any combination of these or other suitableverifying steps may be performed.

As shown in FIG. 29F, the method may further include unexpanding (e.g.,retracting) the displacement mechanism S270 after allowing the anchortip to fixate within the tissue. Unexpanding the displacement mechanismfunctions to substantially restore normal operation of the tissue (e.g.reducing occlusion in the right ventricle while the electrode array iscoupled to the interventricular septum) and/or to enable withdrawal ofthe lead body from the tissue (e.g. through the cardiovascular system).Unexpanding the displacement mechanism preferably includes deflating theballoon displacement mechanism. Deflating the balloon may includewithdrawing fluid from the balloon by suction (e.g. withdrawal of thesyringe, reverse pump or manual actuation), or otherwise releasing fluidfrom the balloon (e.g. allowing a leak), although other embodimentsinclude any suitable reverse actuation performed in expanding thedisplacement mechanism.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

We claim:
 1. A device configured to position an electrode in tissue in abody, comprising: an elongate body having a distal portion, wherein thedistal portion of the elongate body includes an atraumatic tip formedfrom a soft, compressible material which reduces the risk of tissuepenetration; an electrode array coupled to the distal portion of theelongate body; an anchoring element disposed within the elongate bodyand having a distal anchor tip, wherein the anchoring element is movablebetween a first configuration in which the distal anchor tip issubstantially retracted within the elongate body, and a secondconfiguration in which the anchoring element extends at least partiallyfrom one side of the elongate body, the anchoring element beingconfigured to penetrate and fixate within the tissue adjacent to saidone side of the elongate body when in the second configuration; and aselectively expandable displacement mechanism on a side of the distalportion of the elongate body opposite to said one side and configured toselectively bias both the electrode array and the anchoring element in adirection toward the tissue when the selectively expandable displacementmechanism is expanded on the side of the elongate body opposite to saidone side.
 2. The device of claim 1, wherein the distal portion of theelongate body defines an aperture proximate to the electrode array,wherein in the second configuration the distal anchor tip is configuredto be at least partially extended through the aperture.
 3. The device ofclaim 1, wherein the electrode array includes a plurality of electrodes.4. The device of claim 3, wherein at least a portion of the plurality ofelectrodes is arranged serially along a length of the distal portion ofthe elongate body.
 5. The device of claim 1, wherein the electrode arrayincludes stimulation electrodes.
 6. The device of claim 1, wherein: inthe first configuration, the anchoring element is positioned at a firstanchoring element position within the elongate body; and in the secondconfiguration, the anchoring element is positioned at a second anchoringelement position longitudinally displaced from the first anchoringelement position.
 7. The device of claim 6, wherein the anchoringelement is configured to be repetitively moved between the firstconfiguration and the second configuration.
 8. The device of claim 6,further comprising an actuator telescopically disposed within theelongate body, wherein the actuator is configured to engage theanchoring element to move the anchoring element from the first anchoringelement position to the second anchoring element position.
 9. The deviceof claim 8, wherein the actuator is configured to abut at least aportion of the anchoring element.
 10. The device of claim 8, wherein theactuator is configured to be rotationally decoupled from the anchoringelement.
 11. The device of claim 8, further comprising a sleeve coupledto the anchoring element and telescopically engaged within the elongatebody.
 12. The device of claim 11, wherein the actuator is configured tobe telescopically engaged within the sleeve and freely rotatable withinthe sleeve such that rotation of the actuator does not correspond torotation of the anchoring element.
 13. The device of claim 11, whereinthe sleeve is coupled to the actuator.
 14. The device of claim 8,wherein at least a portion of the actuator defines a cut longitudinallyalong and circumferentially around the actuator.
 15. The device of claim8, further comprising a housing coupled to the elongate body.
 16. Thedevice of claim 15, wherein the housing includes a slide coupled to theactuator, the slide having a first slide position corresponding to thefirst anchoring element position and the first configuration of theanchoring element, and a second slide position corresponding to thesecond anchoring element position and the second configuration of theanchoring element.
 17. The device of claim 16, wherein the slide isspring-loaded and biased towards the second slide position.
 18. Thedevice of claim 16, wherein the housing includes a trigger releaseselectively engaged with the actuator, wherein when the trigger releaseis disengaged from the actuator, the actuator is free to travel from thefirst slide position to the second slide position.
 19. The device ofclaim 18, wherein the housing includes a reload switch that retracts theslide from the second slide position to the first slide position. 20.The device of claim 15, wherein the housing is selectively decoupleablefrom the elongate body.
 21. The device of claim 20, wherein the actuatoris selectively decoupleable from the anchoring element.
 22. The deviceof claim 20, wherein the actuator is further selectively decoupleablefrom the elongate body.
 23. The device of claim 1, wherein the distalanchor tip is at least partially curled when the anchoring element is inthe second configuration.
 24. The device of claim 23, wherein when theanchoring element is in the second configuration, the distal anchor tiphas an approximately uniform radius of curvature.
 25. The device ofclaim 1, wherein the elongate body defines a channel within which theanchoring element is disposed, such that the channel restricts theanchoring element to a particular rotational orientation.
 26. The deviceof claim 1, further comprising a second anchoring element disposedwithin the elongate body and having a second distal anchor tip.
 27. Thedevice of claim 26, wherein the distal anchor tip and the second distalanchor tip are at least one of longitudinally distributed along thedistal portion of the elongate body and circumferentially distributedaround the distal portion of the elongate body.
 28. The device of claim1, wherein the anchoring element includes a conductive material suchthat the anchoring element is operable as an electrode.
 29. The deviceof claim 1, wherein the selectively expandable displacement mechanismincludes an inflatable balloon.
 30. The device of claim 29, wherein theinflatable balloon includes an elastic tube sealed around the distalportion of the elongate body.
 31. The device of claim 29, wherein theinflatable balloon is configured to expand only on a side of theelongate body.
 32. The device of claim 1, further comprising anelectrical subsystem configured to signal when the anchoring element isin the second configuration and fixated in the tissue.
 33. The device ofclaim 32, wherein the electrical subsystem includes a circuit that isconfigured to be triggered when the anchoring element is in the secondconfiguration.
 34. The device of claim 33, wherein the electricalsubsystem is configured to signal when the anchor tip is in contact withthe electrode array or when the the anchor tip is not in contact withthe electrode array.
 35. The device of claim 1, further including aseptum configured to prohibit a substantial pressure differentialbetween an internal portion of the elongate body and a region outsidethe elongate body.
 36. The device of claim 1, wherein: in the firstconfiguration, the anchoring element is positioned at a first anchoringelement position within the elongate body; and in the secondconfiguration, the anchoring element is positioned at a second anchoringelement position rotationally displaced from the first anchoring elementposition.
 37. The device of claim 1, wherein the selectively expandabledisplacement mechanism comprises an expandable and retractable ring, ascaffold, or a coil.
 38. A device configured to position an electrode intissue in a body, comprising: an elongate tubular body having at leastone lumen disposed axially therethrough and a distal portion with a wallthat defines at least one aperture on one side thereof; at least onestimulation electrode coupled to the distal portion of the elongate bodyproximate to the at least one aperture; a plurality of anchoringelements disposed within the elongate body, wherein each of theplurality of anchoring elements has a distal anchor tip and isselectively operable in two configurations: a first configurationwherein each anchoring element is at a first anchoring element positionand the distal anchor tip is at least partially uncurled andsubstantially retracted within the at least one lumen of the elongatebody; and a second configuration wherein each anchoring element is at asecond anchoring element position and the distal anchor tip at leastpartially extends through an aperture to form a curled loop configuredto penetrate and fixate within the tissue adjacent to said one side ofthe elongate body; a balloon, coupled at least partiallycircumferentially around the distal portion of the elongate tubular bodyon a side opposite to that of the at least one aperture, that isselectively expandable to bias the at least one stimulation electrodeand the plurality of anchoring elements toward the tissue when theballoon is expanded on the side opposite to that of the at least oneaperture; and an actuator shaft coupled to the anchoring element toactuate the anchoring element between the first and second anchoringelement positions, wherein the actuator shaft is slidably mounted in theat least one lumen to axially and selectively displace the anchoringelements to extend the distal anchor tips to curl through the at leastone aperture and to retract distal anchor tips to uncurl in the at leastone lumen.
 39. The device of claim 38, wherein the at least onestimulation electrode comprises a ring electrode.
 40. The device ofclaim 38, wherein the at least one stimulation electrode comprises aplanar, circular, or elliptical electrode.
 41. The device of claim 38,further comprising a handle coupled to the elongate body.
 42. The deviceof claim 41, wherein the handle includes a slide coupled to the actuatorshaft, the slide having first and second slide positions correspondingto the first and second anchoring element positions, respectively. 43.The device of claim 42, wherein the slide is spring-loaded.
 44. Thedevice of claim 38, wherein each of the plurality of anchoring elementscomprises a shape memory alloy.
 45. The device of claim 44, wherein theshape memory alloy comprises nitinol.